Most traffic accidents result from lack of responsiveness to situations due to drivers' carelessness and cognitive load. In contrast, drivers' drowsiness or unconscious state may cause a big accident but the number of cases is relatively small.
In particular, a driving pattern of a driver in a cognitive load state is not easily differentiated from a driving pattern of a concentrative operation state in a simple driving level, but when a driving environment is rapidly changed, a driver in the cognitive load state has a low response speed in response, which may end up with a traffic accident.